1. Field of the Invention
The present invention relates to a sliding roller bearing obtained by improvement of a small roller bearing comprising inner and outer cylinders and a plurality of cylindrical rollers which are circumferentially spaced apart from each other intervening between inner and outer cylinders.
2. Description of the Related Art
Generally, a roller bearing is characterized in that rolling members, such as balls and rollers, used as machine elements susceptible to a load are rolled between inner and outer races. The typical examples of this type of bearing are shown as follows; a conventionally known ball bearing in FIG. 5; a cylindrical roller bearing in FIG. 6; a shell type needle roller bearing in which the needle rollers roll between the outer race and the shaft in FIGS. 7 and 8; and a solid type needle roller bearing in which the needle rollers roll between inner and outer rollers in FIG. 9. The foregoing conventional roller bearings are constructed such that the rollers rotate and revolve, thus withstanding a load by rolling contact.
In the needle roller bearing among the above-mentioned roller bearings, the needle rollers are retained by a retainer and intervene between the shaft and the outer race, or between the inner and outer races. When the thin needle rollers, that is the needles, rotate, they are likely to skewed and further twisted, thus impairing endurance and causing noises and vibration.
Also, when hardened thin needles are used for a conventional bearing with a view to increasing loadcarrying capacity, stress occurring on a contact point is likely to increase locally. Hence, the load cannot be supported completely only by rolling the rollers. Further, when the shaft diameter is small, the number of needles for supporting the shaft is inevitably decreased, and therefore, the carrying capacity per one needle must be increased.
Concerning lubrication, the use of the needle roller bearing in the oil causes no problem, whereas grease lubrication easily causes grease scattering, thus impairing endurance. On the other hand, the use of a seal also causes some problems such as the enlargement of the periphery of the bearing and troublesome handling.